From owner-freebsd-questions Fri Jan 24 16: 3:39 2003 Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 96F4137B401 for ; Fri, 24 Jan 2003 16:03:37 -0800 (PST) Received: from pursued-with.net (adsl-66-125-9-242.dsl.sndg02.pacbell.net [66.125.9.242]) by mx1.FreeBSD.org (Postfix) with ESMTP id 06C6D43E4A for ; Fri, 24 Jan 2003 16:03:32 -0800 (PST) (envelope-from Kevin_Stevens@pursued-with.net) Received: from babelfish (babelfish [192.168.168.42]) by pursued-with.net (8.12.6/8.12.5) with ESMTP id h0P03VBr012361 for ; Fri, 24 Jan 2003 16:03:31 -0800 (PST) (envelope-from Kevin_Stevens@pursued-with.net) Date: Fri, 24 Jan 2003 16:03:31 -0800 (PST) From: Kevin Stevens Reply-To: Kevin_Stevens@pursued-with.net To: freebsd-questions@freebsd.org Subject: Filesystem tuning parameters Message-ID: <20030124160148.R12356@babelfish.pursued-with.net> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG I have a confusion about apparent conflicts between the minfree setting and time/space optimization. Per the manpage: minfree - Specify the percentage of space held back from normal users; the minimum free space threshold. The default value used is 8%. This value can be set to zero, however up to a factor of three in throughput will be lost over the performance obtained at a 10% threshold. Settings of 5% and less force space optimization to always be used which will greatly increase the overhead for file writes. space/time - The filesystem can either try to minimize the time spent allocat- ing blocks, or it can attempt to minimize the space fragmentation on the disk. Optimization for space has much higher overhead for file writes. The kernel normally changes the preference automat- ically as the percent fragmentation changes on the filesystem. I have a large (120GB) drive dedicated to data storage. I don't want to commit 10% (12GB) of space to free space, and I don't need nearly that much to avoid overflowing the volume. However, I want to maintain time optimization. When it says that "settings of 5% and less force space optimization to be used", is that still the case when you specify time optimization?? Also, why is "up to a factor of three in throughput" lost over the 10% setting? Is that another allusion to space optimization going into effect, or is there something else happening? I guess I don't understand the ramifications of the minfree setting. Any suggestions or references? Thanks! KeS To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message